Specialist Gregg Maloney, left, and trader Tom Ferrigno work on the floor of the New York Stock Exchange Friday, Feb. 8, 2013. (AP Photo/Richard Drew)

A jump in energy-related exports and a steep decline in oil imports lowered the U.S. trade deficit in December to nearly a three-year low.

The improvement suggests the economy grew in the October-December quarter instead of shrinking as the government estimated last week.

A brighter outlook for trade also illustrates how a boom in oil and gas production is reducing crude oil imports and making the U.S. a leader in the export of fuels. And it shows that higher domestic sales of fuel-efficient cars are lowering dependence on oil.

The trade gap fell nearly 21 percent in December from November to $38.6 billion, the Commerce Department said Friday.

Total exports rose 2.1 percent to $186 billion, driven in part by record exports of gasoline, diesel and other fuels.

At the same time, imports declined 2.7 percent to $225 billion. That was largely because oil imports plunged to 223 million barrels - the fewest in 15 years.